BBC Olympics presenter Gary Lineker has expressed his regret that the corporation is not broadcasting the Paralympics, after Channel 4's live coverage of the opening ceremony attracted a peak audience of more than 11 million for the rival broadcaster.

Despite complaints on Twitter from some viewers about advertising breaks and the tone of Jon Snow's commentary on the parade of athletes, Channel 4 executives were delighted with the ratings, which vindicated their surprise bid for the TV rights to the London Paralympics two years ago.

The audience for the Paralympics opening ceremony was about five times what Channel 4 would normally expect on a Wednesday night. Channel 4 was also the most watched UK channel on Wednesday with an audience share for the whole day of nearly 20%, giving the network a rare ratings victory over BBC1 and ITV1.

Lineker, part of the BBC's highly-praised coverage of the London Olympics, said yesterday that he had been inundated with queries about why the BBC was not also the TV home of the Paralympics.

Channel 4 effectively left the BBC in the starting blocks with a knock-out bid for TV rights to the 2012 Paralympics of £8m-£9m, following a tender process run by the London Organising Committee of the Olympic Games. The BBC has the radio rights, with live coverage on BBC Radio 5 Live, 5 Live Extra and online.

However, two years after losing the TV rights to the Paralympics regret still runs deep at the BBC, with one senior TV industry executive describing it as "one of the biggest mistakes of all time".

"From a remit and prominence point of view it has to be viewed as one of the biggest mistakes of all time for the BBC," he said. "It is part of the BBC's remit to support exactly this sort of minority event, and given the massive momentum of the Olympics it is a giant lost opportunity to not be able to continue seamless weeks of promotion to drive the Paralympics after such a spectacular Olympics."

A BBC spokesman admitted the disappointment lingers, but said the corporation is glad that the Paralympics went to a free to air rival rather than pay-TV.

"The BBC are disappointed to have not been awarded the rights to the 2012 Paralympic Games," said a spokesman for BBC Sport. "We're proud of our traditions and record in covering disability sport. However we are pleased that the Games will be available to free-to-air audiences, and we congratulate Channel 4 on securing the rights. We are sure the 2012 Paralympics will be a great success. We wish Channel 4 the best of luck."

There has been limited cooperation between the two broadcasters to promote the Paralympics, with the BBC twice airing Channel 4's Meet the Superhumans promo for its coverage during its programme.

In its 2010 bid, the BBC had drawn up plans to give the event a similar level of mainstream coverage as Channel 4, with programming running all day on BBC1 switching to evening coverage on BBC2.

"People were absolutely gutted at not getting the TV rights," said one BBC source. "There was surprise and disappointment, shell-shock, as there were big plans. It was regretted at the time and it is regretted now, but it was a big bid by Channel 4."

"Locog came to us, all the public service broadcasters were offered to tender," says Martin Baker, director of commercial affairs at Channel 4. "It was a fair fight."

Channel 4 expects to do a little better than break even commercially with its Paralympics coverage, but in terms of viewing the broadcaster has high hopes good ratings will continue to be delivered.

"We are optimistic," said Baker. "We have got a fantastic inheritance from the Olympics because it was so successful. It is true it is a smaller event, but there is so much passion and interest that we are hoping it will do well."

Responding to criticism of the number of commercial breaks during the opening ceremony, a Channel 4 spokesman said that a decision had been taken to reduce advertising airtime to a minimum in order to reduce interruptions to the coverage.

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